A. Field
The present invention relates to a dispenser or vial pump.
B. Related Art More specifically the present invention relates to dispensers or vial pumps as used to dispense or distribute a liquid or gaseous product.
It is generally known that such dispensers or vial pumps mainly consist of a valve assembly which is fixed on top of a container filled with said product to be distributed and of a tube which is fixed with one extremity to a nipple of said valve assembly and which extends with its other extremity towards the bottom of said container.
An important requirement for the dispenser or vial pump is to provide a strong retention force of the tube on the nipple, as otherwise, the tube may detach from the nipple, rendering the dispenser or vial pump inoperative.
Another important requirement for the dispenser or vial pump is that the connection between said nipple and said tube is impermeable to the product in said container, since any leakage involves a loss of efficiency of the concerning dispenser or vial pump.
In order to meet the above mentioned requirements, it is generally known to slide the tube over or in said nipple, whereby both the nipple and the tube have a round and smooth contact surface, allowing a tight friction fit between both elements.
An inconvenience of such known dispensers or vial pumps is that they are quite difficult to assemble, especially when both the nipple and the tube are made of materials having a relative high mutual surface friction, such as high density polyethylene (HDPE) or polypropylene (PP).
Indeed, when in this case the tube is slid over or in the nipple at high speed, for example at a rate of 600 assemblies a minute, the tube is likely to upset, resulting in an incomplete assembly or in an assembly with a poor retention force between the nipple and the tube, which is unacceptable, as in this case the tube is likely to detach from the nipple.
In order to overcome this inconvenience, two possible solutions have been presented.
A first known solution is to enlarge the difference in radius between the nipple and the tube in order to enhance the sliding of the tube in or over the nipple.
Unfortunately this solution has the inconvenience that the connection between the nipple and the tube is not tight enough to prevent leakage.
Moreover such an adaptation of the radius of the tube and/or the nipple decreases the retention force of the nipple on the tube, resulting in an increased risk of the tube detaching from the nipple.
A second known solution for allowing a fluent assembly of the tube on or in the nipple is by providing a gliding agent on either the tube or the nipple.
An inconvenience of this solution is that the use of a gliding agent causes a severe reduction of the retention force between the tube and the nipple, allowing the tube to detach easily from said nipple.
Another inconvenience of this solution is that the gliding agent can dissolve in the product contained in said container, with a change of the composition of said product as a consequence.
It is clear that such a change of composition is not only highly unwanted in for example cosmetics, but may also be dangerous in the case of medical applications.